The invention concerns a process and a device for sealing barrier constructions in subterranean galleries, especially in salt mines.
In subterranean mining, the task of sealing hollow spaces relative to a stressing medium, which can be either fluids or gasses, falls to the transversal seals. In horizontal mines, these seals are referred to as barriers or barrier constructions. Through this, both the static, as well as the sealing, function is assigned to the barrier construction material. As to tightness, failures occur frequently, especially in potash and rock salt mining. This can be attributed primarily to the fact that, with conventional transversal seals connected with the mine, crack formations arise in the contact area between the barrier and the mine. The crack formations are due to excessive tensile tensions.
In the case of an imperfect (i.e., permeable) contact between the tight barrier body and the tight mine, the tightness is attained by means of additional sealing elements or sealing measures.
Additional sealing elements may be either a ring seal, for sealing the contact zone on the circumference of the barrier body, or a surface seal, for sealing the entire cross-section, including the contact zone.
As to the physical contact mechanism of the sealing medium, there are different types of seals. Some seals use the pure adhesion effect and other seals use the overpressure effect.
With seals using the pure adhesion effect, the sealing agent may hold and seal in a solid form, such as, for example, bitumen or plastic tracks and/or metal foils. The seals may also hold and seal in plastic to viscous form, such as, for example, clay, bitumen, or a sand asphalt. Such seals hold and seal by means of adhesion effects to the, and its own substance tightness between the, impermeable static solid bodies to be sealed. Differential movements between barrier bodies and mines as a consequence of the static load absorption and load diminution through the blocking construction can impair the adhesive sealing effect. Thus, local or zonal mechanical overstressings of the (originally tight) static support impair the effect of sealing.
Under high mechanical stressing, high fluid pressure, or steep pressure gradients, as well as under strong deformations or differential movements under loads, sealing systems may work in a purely adhesive manner. Such sealing systems can therefore lose their effectiveness under the influence of different damage mechanisms.
In the seals which operate through overpressure, the sealing media stand in solid form, such as, for example, bitumen, under overpressure relative to the pressure of the sealing, fluid, or gaseous stressing medium. This overpressure prevents the penetration of the medium into the contact joints. Adhesion properties of the sealing material may also support this sealing mechanism.
Such a sealing retains its effectiveness if, and as long as, this overpressure operates.
The overpressure of this type of sealing relative to the pressure of the media to be sealed can be produced through mechanically working elements, such as, for example, hydraulic cylinders, hydrostatic overpressure effects, and physical-chemical effects, through sources under overpressure.
Special problems result with sealing in the salt mines, since seepage occurs in the mine through the exchange of substances between salt brine and the mine.
DE-PS No. 195 434 depicts a barrier seal, especially for salt mines, in which the shaft or the gallery is covered before the barrier door with tubbing or brickwork. The barrier door itself lies with its frame against a wedging collar. The sealing in the contact area between the wedging collar and the mine is accomplished through picotages. The space between the tubbing and the mine is filled up with cement. In the cement behind the tubbings or the brickwork, air chambers are formed which are provided as support and pressing chambers, and allow checking of the value and reliability of the seal or the sealing between the cement and the mine. If it should so happen that, for example, the water blocked out is infiltrating as the result of hair-line cracks, then the chambers can be filled with cement in order to again produce a flawless sealing. There is further constructed a system of tubbing, in order to create a new observation chamber. It is disadvantageous that a lasting seal cannot be attained with the standing of incompletely saturated salt solutions as a consequence of back-rinsings from the picotages.
From DE-PS No. 198 375, there is known a mine blocking device for cross-cuttings or galleries in mineral salt or potash salt or the like, or in other soluble mining layers. In order to prevent the barrier position from becoming loose from the water standing behind the barrier to the submerged mining space, so that the salt mine disintegrates and can no longer be maintained, one or several pipe tubings are provided from the surface. Using the tubings, a space sealed between two barriers or barrier doors is filled with a saturated solution of such salts as stand in the transversal cut or the gallery, and are kept under pressure. Through this, it should be recognized that only saturated solutions can flow out through the existing cracks from the submerged and the protected mining space, and can thereby not enlarge the existing cracks. Since, however, the internal intrados of the barrier nonetheless comes into contact with the unsaturated penetration solution, the danger of seepage exists.
Through DE-PS No. 239 992, there are known a process and device for securing mine spaces to be protected against the submerged mine spaces of a salt mine. In order to create a sealing, a cushion of a gaseous or fluid body, which is indifferent to salts, is provided between a barrier door and the water or the brine. Air is suggested as a gas, and oil is suggested as a fluid. A compressor provides for the maintenance of the air cushion. Since sealing, relative to gas pressure, is extraordinarily difficult, and since in either level or slightly inclined galleries, the gas cushion, because of the varying densities of air and salt brine, is not mounted over the entire cross-section, an adequate sealing cannot be attained.
DD-PS No. 135 103 concerns a process for sealing galleries in soluble mine layers. There is positioned before the static support a hollow space section with material which is inert relative to the salt mine (for example, bitumen), and then buffer lye, which is supersaturated relative to the salt mine. Convection and diffusion are kept slight through the filling out of the hollow, cross-sectional space with heaps of debris and blocking walls, and with displaced openings. The possibility of saturation exists with the unsaturated lye. Through the positioning of an overpressure space, which is filled with a material (silicon oil) which is inert relative to the mine and the bitumen, a penetration of the lye into the area of the sealing packagings is impeded, as long as the overpressure can be maintained. From the air side, pressure measurements, sample extractions, and extrusion of buffer lye are undertaken through pipe tubings, and extrusions are carried out, and an overpressure relative to the lye pressure is produced. In order to rule out the appearance of dissolutions, a long hollow space section with a thrust space insulation is provided. This is not completely brought forward to the static support, so that the possibility of sealing the extruding mine area does not occur in the sealing medium. In order to impede or limit the backcreeping of the thrust insulation, the insulation is bound several times in radially running direction slits, which are extruded with plastic. It is disadvantageous that the overpressure in the sealing system must always be adjusted to the pressure of the standing interference media. Such adjustments require the aid of pumps, which are not maintenance-free, cannot maintain the necessary pressure, and cannot be used as long as the barrier is accessible from one side.